This is a very big job, well into the $1300 - $1500 range for just the timing chain replacement, who knows what else it will need when they get in there. Since the vehicle doesn't run there may be other problems too, you just don't know. You have to figure you're going to spend at least $1500 + $1500 = $3000.00 to get this running, if not more. Look to see what else you can get for this much, and figure out what your willing to spend. Look at the overall condition of the vehicle, did the timing chain break due to lack of maintenance? If so, this may have other issues as well. Look at the common problems these have: http://www.consumeraffairs.com/automotive/ford_explorer.html